Liquid crystal display devices and other flat-panel display devices are widely used in various fields as image display devices for personal computers, portable information devices or the like in various kinds; in view of their small depth dimension and small weight as well as small electric power consumption. In particular, the flat-panel devices have come to be widely used as the image-displaying devices for; the television sets, ranging from small portable ones to big wall hanging ones; small laptop computers, and other portable information terminals; and car navigation systems or the like.
In following, a light transmissive one of the active-matrix LCD devices is exemplified for explaining its construction.
An active-matrix LCD device is comprised of a matrix array substrate (hereinafter referred as array substrate) and a counter substrate, which are closely opposed to each other with a predetermined gap, and of a liquid crystal layer held in the gap.
The array substrate has signal lines and scanning lines, which are arranged in a latticework on an insulator substrate such as a glass plate, and are overlapped to sandwich an insulator film. On each rectangular patch defined by the signal and scanning lines, a pixel electrode is disposed and formed of a transparent electro-conductive material such as Indium-doped tin oxide (ITO). At around each crossing of the signal and scanning lines, a pixel-switching element is disposed for controlling a respective pixel electrode. When the pixel-switching element is a thin film transistor (TFT), gate and signal electrodes of the TFT are respectively connected with scanning and signal lines; and a source electrode of the TFT is connected with a pixel electrode. The counter substrate has a counter electrode formed of a transparent electro-conductive material such as indium-doped tin oxide (ITO), on an insulator substrate such as a glass plate. When to realize color display, color filter layers are formed on the counter or array substrate.
On the fringe part of the flat-panel display device, for example, the array substrate protrudes from an edge of the counter substrate as to form a shelf region, at along a fringe along length direction or width direction of the substrates. Onto the shelf region, arranged in a row or rows are connector pads for inputting of driving signal from outside into the signal lines and/or scanning lines. As ways for arranging driver IC chips on the fringe part as to input the signal to the connector pads, adopted are “outer lead bonding” (OLB) and “chip on glass” (COG) arrangements. In the “outer lead bonding” (OLB) arrangement, rectangular flexible circuit boards referred as tape carrier packages (TCPs) are mounted on the shelf region. In the “chip on glass” (COG) arrangement, the driver ICs are directly mounted on the shelf region. On most occasions for such mounting, electrically conductive stuff such as anisotropic conductive film (ACF) or the like is used to attach and mount onto the shelf regions, electric terminal faces at ends of the TCPs or terminal-arranging reverse faces of the driver IC chips. In other words, “face-down mounting” is adopted. Such mounting procedure is performed usually by using a heat-press tool so that the ACF, which has been attached on reverse faces of the driver IC chips for example, is heat-pressed at 170-200° C. for 10-20 seconds.
In following, a typical construction of the fringe part is explained exemplarily for the COG arrangement. A shelf region along a length-direction fringe (X fringe) of the flat-panel display device is mounted with a plurality of the driver IC chips that are the X-side driver IC chips for inputting image signals, i.e. data signals, to the signal lines; and another shelf region along a width-direction fringe (Y fringe) is mounted with one or more of the driver IC chips as the Y-side driver IC chip(s) for inputting gate voltage for driving TFTs, consecutively to the scanning lines.
For inputting the signals to the X-side and Y-side driver IC chips, a long band-shaped flexible printed circuit board, which is to be abbreviated as FPC hereinafter, is used as arranged along the X fringe, for example; and signal inputting to the driver IC chips is made through FPC-IC connecting wirings that have been formed by a patterning on beforehand, on the shelf region.
Assembling process of flat-panel display devices are exemplified by follows. A reverse frame for receiving or upbearing the display panel is assembled with a bezel cover as an obverse frame by fixing with screwing or the like as to clamp marginal part of the display panel and thereby secure the display panel. On course of such assembling, the display panel is positioned to a predetermined location, by rib-shaped projections on the reverse frame. Then, in such an aligned state, the display panel and the bezel cover are secured to be non-shiftable onto the reverse frame. When the flat-panel display device is of a backlight type, a surface illuminant device is arranged on reverse face of the display panel. In general, a light-guide plate of the surface illuminant device is received within the reverse frame.
On course of manufacturing the flat-panel display devices, “dynamic operating inspection” is made when the driver IC chips are mounted on the display panel in order to know whether all pixels make normal operation. If and when imaging defect on the screen is found on such inspection, a faulty portion has to be determined; and various investigations for facilitating such determining have been made. Please see JP-2005-115129A or Japan's patent application publication No. 2005-115129. The dynamic operating inspection may reveal that a row of pixel along a signal line exhibits the imaging defect referred as a line defect, and the line defect may be considered to be due to defect of the driver IC chip. In such occasion, the driver IC chip associated with the line defect is picked off and then new one is mounted as a replacement.